Historically, grease traps have been used in restaurants and other commercial facilities to limit the amount of grease and solid waste that is carried into sewer systems via waste water. Typical grease traps are either passive grease traps or automatic grease traps. Passive grease traps are usually emptied less regularly than automatic grease traps and therefore waste tends to build up inside the tank. Passive grease traps typically include a tank with an inlet that brings in waste water and an outlet that carries water out of the system. Lightweight grease rises to the top of the tank and heavier solids settle in the bottom of the tank.
A problem with many grease traps is that water may flush through the system with such velocity that it disrupts the grease that has already separated, causing the waste to be expelled with grey water. This is especially true as the tank fills up with grease, so that the grease/water interface is closer to the grease trap bottom. As a result, the passive tanks still have to be monitored for content levels and cleared of grease regularly in order to maintain higher grease removal efficiency. Emptying the grease from the passive traps typically has to be scheduled and can be intrusive and inconvenient for businesses. Often, the grease traps are operating at lower efficiency levels by the time the grease content is noticed and/or the traps are required to operate at capacity for longer periods of time to allow for scheduling of grease removal. Grease traps are often not easily accessible for grease removal and FOG accumulation on the trap parts can make grease removal even more difficult. Such traps can be difficult to originally position and also to repetitively access when grease removal is needed.
As such, grease traps, though effective to remove some grease and solid waste from solids containing liquids, may not adequately prevent grease from going downstream with the water and remain challenging for grease removal. Thus there remains a need for a low cost, more effective grease trap for removing solids and grease from wastewater.